An easy-to-clean solder paste and its preparation method

Abstract

This application is a divisional application of application number 2023103071686. The present invention belongs to the field of soldering material technology. This application provides an easy-to-clean solder paste and its preparation method, which is composed of solder, flux, additives and solvent. The flux uses a water-washable film-forming agent instead of traditional rosin, which makes the flux have good hydrophilicity. During the soldering process, it reduces the adhesion between the solder slag and the substrate. After the soldering is completed, it can be washed with water, which reduces the risk of the cleaning solvent corroding the substrate. No VOCs are generated during the washing process, which is beneficial to human health and environmental protection. It has the advantages of low residue, good water washing effect, low implementation cost and easy promotion and implementation.

Description

[0001] This application is a divisional application. The original application has the application number 2023103071686, the application date is March 27, 2023, and the invention title is "Environmentally friendly, low-residue, easy-to-clean solder paste and its preparation method". Technical Field

[0002] This invention belongs to the field of soldering materials technology, specifically relating to an easy-to-clean solder paste and its preparation method. Background Technology

[0003] Solder paste is a new type of soldering material that emerged with the development of surface mount technology (SMT). It is a paste-like mixture of solder powder, flux, and other components. It is mainly used for soldering electronic components such as resistors, capacitors, and ICs on PCB surfaces in the SMT industry. Traditional solder pastes commonly use rosin or modified rosin as flux. During the soldering process, flux residue may remain on or near the solder joint, which may lead to a deterioration of the soldering area and impair the contact effect of the pins of electronic components soldered with solder paste. Furthermore, the resistivity of the residue decreases after absorbing moisture from the air, which increases the risk of short circuits in electronic components. Existing solder pastes are generally washed with organic solvents after soldering, which takes a long time and poses a risk of corroding the substrate. The washing process also generates VOCs, which are detrimental to human health and environmental protection. There is an urgent need for an easy-to-clean solder paste. Summary of the Invention

[0004] In order to solve the technical problems of high residue, difficulty in cleaning, and generation of VOCs harmful to human health during the cleaning process, this invention proposes an easy-to-clean solder paste.

[0005] The second objective of this invention is to provide a method for preparing an easy-to-clean solder paste.

[0006] To achieve the first objective, this application adopts the following approach:

[0007] An easy-to-clean solder paste, comprising the following components by weight: 78-85 parts solder, 12-19 parts flux, 1-2 parts additives, and 3-5 parts solvent;

[0008] The solder is composed of the following components by mass fraction: tin 90.89-92.78 wt%, copper 5.51-7.01 wt%, and silver 1.65-2.11 wt%.

[0009] Preferably, the method for preparing the solder includes the following steps:

[0010] S401. Weigh each component of the solder according to the stated mass fraction and melt them to obtain liquid solder;

[0011] S402. Pour the liquid solder obtained in step S401 into a mold and cool it to room temperature to obtain a solder brick;

[0012] S403. After crushing the solder bricks obtained in step 402, use a ball mill in conjunction with a high-pressure homogenizer to ball mill them to a particle size of 18-41μm to obtain the final product.

[0013] Preferably, the additive is composed of the following components by weight: 0.5-1 parts of stabilizer and 0.5-1 parts of dispersant, wherein the stabilizer is p-phenol.

[0014] Preferably, the solvent is a 2:1:1 mixture of ethanol, ethyl acetate, and butyl acetate.

[0015] Preferably, the flux is composed of the following components by weight: 6-8 parts water-washable film-forming agent, 2-4 parts activator, 1-2 parts thixotropic agent, 0.5-1 part etching inhibitor, and 0.5-1 part wetting agent.

[0016] Preferably, the thixotropic agent is a 1:1:1 mixture of glyceryl tri-12-hydroxystearate, polyamide, and stearamide, the etching inhibitor is benzotriazole, and the wetting agent is OP-10.

[0017] Preferably, the water-washing film-forming agent is composed of the following components in parts by weight: 2-3 parts modified wheat starch, 4-5 parts modified acrylic resin, 1-2 parts surfactant, and 2-3 parts deionized water. More preferably, the surfactant is sodium dodecylbenzenesulfonate.

[0018] Preferably, the method for preparing the modified wheat starch includes the following steps:

[0019] Step 101. Centrifuge the crude wheat starch in a starch centrifuge at 1000-1300 rpm for 30-40 minutes, then filter and dry to obtain refined starch.

[0020] Step 102. Add the refined starch obtained in step 101 into a magnetically stirred tank containing glycerol, and add titanate coupling agent and anhydrous ethanol dropwise in sequence. Stir at 200-300 rpm for 5-10 min, and then stir at 500-1200 rpm for 0.5-2.5 h to obtain modified wheat starch. The mass ratio of glycerol to refined starch is 1-2:1. Anhydrous ethanol is used to adjust the viscosity of the system and ensure the stirring rate.

[0021] In practical applications, starch centrifuges can centrifuge and settle proteins and type B starch in crude wheat starch. Centrifugation can improve the film-forming ability and hydrophilicity of modified starch. Adding refined starch, titanate coupling agent, and anhydrous ethanol to glycerol can further enhance the hydrophilicity and film-forming properties of the modified starch system. On the one hand, it facilitates covering the solder joints during soldering to prevent oxidation. On the other hand, after soldering, the modified starch has weak adsorption to the substrate, and the modified wheat starch is highly hydrophilic, making it easy to peel off after contact with water or anhydrous ethanol. By using a water-washable film-forming agent instead of traditional rosin in the flux, the flux has good hydrophilicity. During soldering, the adhesion between the solder slag and the substrate is reduced. After soldering, it can be washed with clean water, reducing the risk of corrosion of the substrate by the cleaning solvent. No VOCs are generated during the washing process, which is beneficial to human health and environmental protection. It has the advantages of low residue, good water washing effect, low implementation cost, and easy promotion and implementation.

[0022] Preferably, the preparation of the modified acrylic resin includes the following steps: acrylic resin, castor oil alkyd resin, polyurethane resin, and anhydrous ethanol are sequentially added to a stirred tank and stirred at 300-500 rpm for 5-10 min. After stirring, DMAEMA is added dropwise and stirred at 800-900 rpm for 20-40 min to obtain the modified acrylic resin. More preferably, the mass ratio of acrylic resin, polyurethane resin, anhydrous ethanol, and DMAEMA is 6-9:1:2:0.5.

[0023] In practical applications, on the one hand, castor oil alkyd resin, polyurethane modified resin, and DMAEMA are used to modify acrylic resin, introducing a large number of hydroxyl and carboxyl groups into the acrylic resin, thereby improving the hydrophilicity of the modified acrylic resin itself. On the other hand, a large number of amino flexible groups are introduced, giving the solder paste a good spread rate during the soldering process, facilitating electronic printing, saving solder in the solder paste, and preventing solder joint oxidation during the soldering process. By using a water-washable film-forming agent in the flux instead of traditional rosin, the flux has good hydrophilicity, reducing the adhesion between the solder slag and the substrate during the soldering process. After soldering, it can be washed with clean water, reducing the risk of cleaning solvents corroding the substrate. No VOCs are generated during the washing process, which is beneficial to human health and environmental protection. It has the advantages of low residue, good water washing effect, low implementation cost, and easy promotion and implementation.

[0024] Preferably, the preparation method of the water-washable film-forming agent includes the following steps: adding modified acrylic resin, surfactant, modified wheat starch and deionized water into a stirring vessel in sequence, stirring for 20-40 minutes in a constant temperature water bath at 30-40℃ and 500-700 rpm, and cooling to room temperature after stirring to obtain the film-forming agent.

[0025] Preferably, the activator is composed of the following components by weight: 5-7 parts anhydrous citric acid, 2-4 parts malic acid, 0.1-0.8 parts triethanolamine, and 7-11 parts acrylic resin.

[0026] Preferably, the method for preparing the activator includes the following steps:

[0027] Step 201. Add anhydrous citric acid, malic acid and triethanolamine into a stirred tank in sequence, and stir for 0.5-1.2 hours in a water bath at 30-50℃ and 300-520 rpm to obtain the active substance body.

[0028] Step 202. Add acrylic resin to the active substance obtained in step 1 and stir for 4-5 hours at 90-120℃ and 600-1200rpm to obtain the active coating.

[0029] Step 203. Dry and cure the active coating obtained in step 202 at 25-30℃ and 200-400rpm. After curing, ball mill the coating to 100-360μm to obtain the activator.

[0030] In practical applications, citric acid and DL-malic acid exhibit a small wetting angle and strong wetting ability on the substrate. They also exhibit poor corrosion resistance at low temperatures, preventing solder paste from corroding the substrate before soldering. During soldering, they effectively remove oxides from the substrate and improve solder spreadability. Acrylic resin coating prevents the volatilization and oxidation of citric acid and DL-malic acid, further protecting the substrate at low temperatures and preventing corrosion by activators. The use of a water-washable film-forming agent instead of traditional rosin in the flux provides excellent hydrophilicity, reducing the adhesion between solder slag and the substrate during soldering. After soldering, the flux can be washed with water, reducing the risk of corrosion from cleaning solvents. The washing process does not generate VOCs, benefiting human health and the environment. It boasts advantages such as low residue, good water washing effect, low implementation cost, and ease of promotion and implementation.

[0031] To achieve the second objective, this application adopts the following technical solution:

[0032] A method for preparing an easy-to-clean solder paste includes the following steps:

[0033] S301. Add the water-washing film-forming agent, activator, thixotropic agent, etching inhibitor, and wetting agent sequentially into a stirred tank and stir for 20-30 minutes at 40-50℃ and 300-420rpm to obtain the flux.

[0034] S302. Solder, flux, additives and solvent are added sequentially into a vacuum mixing vessel and stirred for 3-7 hours at 25-35℃ and 400-620rpm to obtain easy-to-clean solder paste.

[0035] Preferably, nitrogen gas needs to be introduced during the stirring process in step S302, and the vacuum degree of the vacuum stirring vessel is 0.03-0.04 MPa.

[0036] Compared with the prior art, this application has the following beneficial effects:

[0037] 1. This application provides an easy-to-clean solder paste, which is composed of solder, flux, additives, and solvent. The flux uses a water-washable film-forming agent instead of traditional rosin, giving the flux good hydrophilicity. During the soldering process, it reduces the adhesion between the solder slag and the substrate. After soldering, it can be washed with clean water, reducing the risk of corrosion of the substrate by the cleaning solvent. No VOCs are generated during the washing process, which is beneficial to human health and environmental protection. It has the advantages of low residue, good water washing effect, low implementation cost, and easy promotion and implementation.

[0038] 2. This application provides a method for preparing an easy-to-clean solder paste, which is prepared by stirring solder, flux, additives and solvent in a vacuum environment. The easy-to-clean solder paste has the advantages of wide application, low environmental pollution, simple operation, strong reproducibility and low implementation cost. Detailed Implementation

[0039] The present invention will be further described below with reference to Tables 1 and 2, specific embodiments 1-3, and comparative example 1:

[0040] (1) The preparation method of solder includes the following steps:

[0041] S401. Weigh each component of the solder according to the stated mass fraction and melt them to obtain liquid solder;

[0042] S402. Pour the liquid solder obtained in step S101 into a mold and cool it to room temperature to obtain a solder brick;

[0043] S403. After rolling and crushing the solder bricks obtained in step 102, use a ball mill in conjunction with a high-pressure homogenizer to ball mill to a particle size of 40μm to obtain the final product.

[0044] Example 1

[0045] The preparation method of modified wheat includes the following steps:

[0046] S101. After centrifuging the crude wheat starch in a starch centrifuge at 1105 rpm for 32 min, refined starch is obtained.

[0047] S102. The refined starch obtained in S101 is put into a magnetically stirred tank containing glycerol, and titanate coupling agent and anhydrous ethanol are added dropwise in sequence. After stirring at 257 rpm for 6 min, it is stirred at 980 rpm for 0.7 h to obtain modified wheat starch.

[0048] The preparation method of modified acrylic resin includes the following steps:

[0049] Acrylic resin, castor oil alkyd resin, polyurethane resin, and anhydrous ethanol were added to a mixing tank in a mass ratio of 6.5:1:2:0.5 and stirred at 375 rpm for 6 minutes. After stirring, DMAEMA was added dropwise and stirred at 818 rpm for 22 minutes to obtain the modified acrylic resin.

[0050] The preparation method of the water-washable film-forming agent according to the weight parts shown in Table 2 includes the following steps:

[0051] Modified acrylic resin, surfactant, modified wheat starch, and deionized water are sequentially added to a mixing tank and stirred for 20-40 minutes in a constant temperature water bath at 30-40℃ and 500-700 rpm. After stirring, the mixture is cooled to room temperature to obtain the final product.

[0052] The preparation method of the activator according to the weight parts shown in Table 3 includes the following steps:

[0053] S201. Anhydrous citric acid, malic acid and triethanolamine are added sequentially to a stirred tank and stirred for 1.1 h at 33°C water bath and 312 rpm to obtain the active substance body.

[0054] S202. Add the active substance obtained in S1 to acrylic resin and stir at 93°C and 630 rpm for 4.1 h to obtain the active coating.

[0055] S203. The active coating obtained in S202 is dried and cured at 27°C and 240 rpm. After curing, it is ball-milled to 108 μm to obtain the activator.

[0056] The preparation method of easy-to-clean solder paste according to the weight parts shown in Table 4 includes the following steps:

[0057] S301. The water-washing film-forming agent, activator, thixotropic agent, etching inhibitor and wetting agent are added to the mixing tank in sequence and stirred at 42°C and 319 rpm for 22 min to obtain the flux.

[0058] S302. Solder, flux, additives and solvent are sequentially added to a vacuum mixing vessel and stirred for 3.6 hours at 28°C, 450 rpm, with nitrogen gas introduced and the vacuum degree of the vacuum mixing vessel is 0.0318 MPa, to obtain easy-to-clean solder paste.

[0059] Example 2

[0060] The preparation method of modified wheat includes the following steps:

[0061] S101. After centrifuging the crude wheat starch in a starch centrifuge at 1244 rpm for 35 min, refined starch is obtained.

[0062] S102. The refined starch obtained in S101 is put into a magnetically stirred tank containing glycerol, and titanate coupling agent and anhydrous ethanol are added dropwise in sequence. After stirring at 257 rpm for 6 min, it is stirred at 620 rpm for 1.1 h to obtain modified wheat starch.

[0063] The preparation method of modified acrylic resin includes the following steps:

[0064] Acrylic resin, castor oil alkyd resin, polyurethane resin, and anhydrous ethanol were added to a mixing tank in a mass ratio of 7.2:1:2:0.5 and stirred at 390 rpm for 7 minutes. After stirring, DMAEMA was added dropwise and stirred at 842 rpm for 27 minutes to obtain the modified acrylic resin.

[0065] The preparation method of the water-washable film-forming agent according to the weight parts shown in Table 2 includes the following steps:

[0066] Modified acrylic resin, surfactant, modified wheat starch, and deionized water were sequentially added to a mixing tank and stirred for 29 minutes at 610 rpm in a constant temperature water bath at 35°C. After stirring, the mixture was cooled to room temperature to obtain the final product.

[0067] The preparation method of the activator according to the weight parts shown in Table 3 includes the following steps:

[0068] S201. Anhydrous citric acid, malic acid and triethanolamine are added sequentially into a stirred tank and stirred for 0.8 h in a water bath at 42°C and 377 rpm to obtain the active substance body.

[0069] S202. Add the active substance obtained in S1 to acrylic resin and stir at 109°C and 811 rpm for 4.5 h to obtain the active coating.

[0070] S203. The active coating obtained in S202 is dried and cured at 28°C and 333 rpm. After curing, it is ball-milled to 147 μm to obtain the activator.

[0071] The preparation method of easy-to-clean solder paste according to the weight parts shown in Table 4 includes the following steps:

[0072] S301. Add the water-washing film-forming agent, activator, thixotropic agent, etching inhibitor and wetting agent into a mixing tank in sequence and stir at 46°C and 365 rpm for 25 min to obtain the flux.

[0073] S302. Solder, flux, additives and solvent are sequentially added to a vacuum mixing vessel and stirred for 4.2 hours at 28°C, 425 rpm, with nitrogen gas introduced and the vacuum degree of the vacuum mixing vessel is 0.0323 MPa, to obtain easy-to-clean solder paste.

[0074] Example 3

[0075] The preparation method of modified wheat includes the following steps:

[0076] S101. After centrifuging the crude wheat starch in a starch centrifuge at 1288 rpm for 36 min, refined starch is obtained.

[0077] S102. The refined starch obtained in S101 is put into a magnetically stirred tank containing glycerol, and titanate coupling agent and anhydrous ethanol are added dropwise in sequence. After stirring at 291 rpm for 9 min, it is stirred at 1155 rpm for 2.3 h to obtain modified wheat starch.

[0078] The preparation method of modified acrylic resin includes the following steps:

[0079] Acrylic resin, castor oil alkyd resin, polyurethane resin, and anhydrous ethanol were added to a mixing tank in a mass ratio of 8.2:1:2:0.5 and stirred at 465 rpm for 7 minutes. After stirring, DMAEMA was added dropwise and stirred at 842 rpm for 37 minutes to obtain the modified acrylic resin.

[0080] The preparation method of the water-washable film-forming agent according to the weight parts shown in Table 2 includes the following steps:

[0081] Modified acrylic resin, surfactant, modified wheat starch, and deionized water were sequentially added to a mixing tank and stirred for 35 minutes at a constant temperature of 37°C and 633 rpm. After stirring, the mixture was cooled to room temperature to obtain the final product.

[0082] The preparation method of the activator according to the weight parts shown in Table 3 includes the following steps:

[0083] S201. Anhydrous citric acid, malic acid and triethanolamine are added sequentially to a stirred tank and stirred for 1.1 h at 46°C water bath and 517 rpm to obtain the active substance body.

[0084] S202. Add the active substance obtained in S1 to acrylic resin and stir at 115℃ and 1125rpm for 4.6h to obtain the active coating.

[0085] S203. The active coating obtained in S202 is dried and cured at 28°C and 369 rpm. After curing, it is ball-milled to 337 μm to obtain the activator.

[0086] The preparation method of easy-to-clean solder paste according to the weight parts shown in Table 4 includes the following steps:

[0087] S301. The water-washing film-forming agent, activator, thixotropic agent, etching inhibitor and wetting agent are added to the mixing tank in sequence and stirred at 46°C and 411 rpm for 25 min to obtain the flux.

[0088] S302. Solder, flux, additives and solvent are sequentially added to a vacuum mixing vessel and stirred for 5.2 hours at 33°C, 605 rpm, with nitrogen gas introduced and the vacuum degree of the vacuum mixing vessel being 0.0351 MPa, to obtain easy-to-clean solder paste.

[0089] Comparative Example 1

[0090] In Example 3, the water-washing film-forming agent in the solder resist was replaced with an equal amount of rosin, while the other components remained unchanged.

[0091] Comparative Example 2

[0092] In Example 3, the water-washing film-forming agent in the solder resist was replaced with an equal weight of rosin, and the activator was replaced with an equal weight of succinic acid after removing acrylic resin, while the remaining components remained unchanged.

[0093] Table 1. Composition of solder mass fraction in Examples 1-3 and Comparative Examples 1-2

[0094]

[0095] Table 2. Composition of water-washing film-forming agents in Examples 1-3 and Comparative Examples 1-2 by weight.

[0096]

[0097] Table 3. Composition of activators by weight in Examples 1-3 and Comparative Examples 1-2

[0098]

[0099] Table 4. Composition of solder paste by weight in Examples 1-3 and Comparative Examples 1-2

[0100]

[0101] Examples 1-3 and Comparative Examples 1-2 were compared according to IPC-TM-650 2.6.3.7:2007, IPC J-STD-004B, IPC-TM-650 2.4.34.3:1995, IPC-TM-650 2.4.45:1995, JIS-Z-31976.6.1, IPC-TM-650 2.3.32D:2004, IPC-TM-650 2.4.46A:2004, IEC 62149-2-21, and IPC-TM-650. 2.3.13:2004 standard was used to test the performance of solder paste and to conduct simulated cleaning experiments with water and ethanol. Solder paste of the same quality as Examples 1-3 and Comparative Examples 1-2 was used on solder pads of the same batch number and soldered for the same duration at the same soldering temperature. After soldering, the test solder pads were respectively immersed in an ultrasonic vibration cleaning tank containing water or ethanol for vibration cleaning. After cleaning until no film-forming material was visually visible on the surface of the test solder pads, the cleaning time was recorded. The test results are shown in Table 5 below.

[0102] Table 5 Test results of Examples 1-3 and Comparative Examples 1-2

[0103]

[0104] As shown in Table 5, in actual use, the starch centrifuge can centrifuge and settle the protein and type B starch in crude wheat starch. After centrifugation, the film-forming ability and hydrophilicity of the modified starch can be improved. Adding refined starch with titanate coupling agent and anhydrous ethanol to glycerol can improve the hydrophilicity and film-forming properties of the modified starch system. On the one hand, it is easy to cover the solder joint during the soldering process to prevent solder joint oxidation. On the other hand, after soldering, the modified starch has weak adsorption capacity to the substrate. Modified wheat starch has strong hydrophilicity and is easy to peel off after contact with water or anhydrous ethanol. By using a water-washable film-forming agent instead of traditional rosin in the flux, the flux has good hydrophilicity. During the soldering process, the adhesion between the solder slag and the substrate is reduced. After soldering, it can be washed with clean water to reduce the risk of corrosion of the substrate by the cleaning solvent. No VOCs are generated during the washing process, which is beneficial to human health and environmental protection. It has the advantages of low residue, good water washing effect, low implementation cost, and easy promotion and implementation.

[0105] In practical applications, on the one hand, castor oil alkyd resin, polyurethane modified resin, and DMAEMA are used to modify acrylic resin, introducing a large number of hydroxyl and carboxyl groups into the acrylic resin, thereby improving the hydrophilicity of the modified acrylic resin itself. On the other hand, a large number of amino flexible groups are introduced, giving the solder paste a good spread rate during the soldering process, facilitating electronic printing, saving solder in the solder paste, and preventing solder joint oxidation during the soldering process. By using a water-washable film-forming agent in the flux instead of traditional rosin, the flux has good hydrophilicity, reducing the adhesion between the solder slag and the substrate during the soldering process. After soldering, it can be washed with clean water, reducing the risk of cleaning solvents corroding the substrate. No VOCs are generated during the washing process, which is beneficial to human health and environmental protection. It has the advantages of low residue, good water washing effect, low implementation cost, and easy promotion and implementation.

[0106] The results of copper plate corrosion test and copper mirror corrosion test show that citric acid and malic acid, as activators, can remove oxides from the surface of solder joints. Under the coating of acrylic resin, they are not easily corroded at low temperatures. Compared with succinic acid, they have a stronger protective effect on the circuit. The results of water / ethanol simulated cleaning test show that after water washing film-forming agent replaces rosin, it significantly improves the water cleanliness of the film-forming material, leaves little residue, is easy to clean, and significantly reduces cleaning time.

[0107] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An easy-to-clean solder paste, characterized in that, The components are composed of the following parts by weight: 78-85 parts solder, 12-19 parts flux, 1-2 parts additives, and 3-5 parts solvent. The flux is composed of the following components by weight: 6-8 parts water-washable film-forming agent, 2-4 parts activator, 1-2 parts thixotropic agent, 0.5-1 part etching inhibitor, and 0.5-1 part wetting agent. The water-washing film-forming agent is composed of the following components by weight: 2-3 parts modified wheat starch, 4-5 parts modified acrylic resin, 1-2 parts surfactant, and 2-3 parts deionized water. The particle size of the solder is 18-41 μm; The method for preparing the modified wheat starch includes the following steps: S101. After centrifuging the crude wheat starch in a starch centrifuge at 1000-1300 rpm for 30-40 minutes, refined starch is obtained. S102. The refined starch obtained in S101 is put into a magnetically stirred tank containing glycerol, and titanate coupling agent and anhydrous ethanol are added dropwise in sequence. After stirring at 200-300 rpm for 5-10 min, it is stirred at 500-1200 rpm for 0.5-2.5 h to obtain modified wheat starch. The preparation method of the activator includes the following steps: S201. Anhydrous citric acid, malic acid, and triethanolamine are sequentially added to a stirred tank and stirred for 0.5-1.2 hours in a water bath at 30-50℃ and 300-520 rpm to obtain the active substance body. S202. Add the active substance obtained in S1 to acrylic resin and stir for 4-5 hours at 90-120℃ and 600-1200rpm to obtain the active coating. S203. The active coating obtained in S202 is dried and cured at 25-30℃ and 200-400rpm. After curing, it is ball-milled to 100-360μm to obtain the activator.

2. The easy-to-clean solder paste according to claim 1, characterized in that, The solder is composed of the following components by mass fraction: tin 90.89-92.78 wt%, copper 5.51-7.01 wt%, and silver 1.65-2.11 wt%.

3. The easy-to-clean solder paste according to claim 1, characterized in that, The preparation of the modified acrylic resin includes the following steps: Acrylic resin, castor oil alkyd resin, polyurethane resin, and anhydrous ethanol are sequentially added to a mixing tank and stirred at 300-500 rpm for 5-10 minutes. After stirring, DMAEMA is added dropwise and stirred at 800-900 rpm for 20-40 minutes to obtain the modified acrylic resin.

4. The easy-to-clean solder paste according to claim 3, characterized in that, The mass ratio of the acrylic resin, polyurethane resin, anhydrous ethanol, and DMAEMA is 6-9:1:2:0.

5.

5. The easy-to-clean solder paste according to claim 1, characterized in that, The preparation method of the water-washable film-forming agent includes the following steps: adding modified acrylic resin, surfactant, modified wheat starch and deionized water into a stirring vessel in sequence, stirring for 20-40 minutes in a constant temperature water bath at 30-40℃ and 500-700 rpm, and cooling to room temperature after stirring to obtain the film-forming agent.

6. The easy-to-clean solder paste according to claim 1, characterized in that, The activator is composed of the following components by weight: 5-7 parts anhydrous citric acid, 2-4 parts DL-malic acid, 0.1-0.8 parts triethanolamine, and 7-11 parts acrylic resin.

7. The easy-to-clean solder paste according to claim 2, characterized in that, The method for preparing the solder includes the following steps: S401. Weigh each component of the solder according to the stated mass fraction and melt them to obtain liquid solder; S402. Pour the liquid solder obtained in step S401 into a mold and cool it to room temperature to obtain a solder brick; S403. After crushing the solder bricks obtained in step 402, use a ball mill in conjunction with a high-pressure homogenizer to ball mill them to a particle size of 18-41μm to obtain the final product.

8. The easy-to-clean solder paste according to claim 1, characterized in that, The thixotropic agent is a 1:1:1 mixture of glyceryl tri-12-hydroxystearate, polyamide, and stearamide; the etching inhibitor is benzotriazole; and the wetting agent is OP-10.

9. The method for preparing easy-to-clean solder paste according to any one of claims 1-8, characterized in that, Includes the following steps: S301. Add the water-washing film-forming agent, activator, thixotropic agent, etching inhibitor, and wetting agent sequentially into a stirred tank and stir for 20-30 minutes at 40-50℃ and 300-420rpm to obtain the flux. S302. Solder, flux, additives and solvent are added sequentially into a vacuum mixing vessel and stirred for 3-7 hours at 25-35℃ and 400-620rpm to obtain easy-to-clean solder paste.

10. The method for preparing the easy-to-clean solder paste according to claim 9, characterized in that, Nitrogen gas needs to be introduced during the stirring process in S302, and the vacuum degree of the vacuum stirring vessel is 0.03-0.04 MPa.

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